Hi,
Is there anything like firejail for android ?

I want to run Opera mini inside a sandbox.

Using Android 4.0.4.

Note : I dont want to root my device.

Wrong OS for that, imho. 4.0.4 is very old and security fixes are needed. Getting a sandbox is hardly the problem you need to fix. android 4.0.4 exploits

Although linux generally is fairly secure, it is not immune, and Android is even less so. You probably will slow things up with a sandbox if you find one to run on 4.0.4 and you cpu, as it's a form of virtualisation. With a 4.0.4 OS, your cpu will be slower than today's. Older implies larger wafer fab on the ICs which in turn mean more current for the same speed and less speed overall, allowing less complexity. You'd be stuck on an earlier Arm 7.

in a way android is built like that, i think each app runs as its own user, and their privileges are strictly defined.

not that that would help - what's opera mini anyway? i seem to remember one of the first phone browsers, 15 years ago? that?

anyhow, enter 'sandbox' here: https://f-droid.org/packages/

The internal memory of this tablet is very low. If I enable automatic updates it results in "low disk space".

This is opera mini https://play.google.com/store/apps/d...ra.mini.native

This is my tablet http://www.gsmarena.com/micromax_fun..._p275-5466.php

If your memory is low, forget sandboxing. They are cagey about ram, and that's a bad sign (< 1G probably). Not great parts or specs. The oldest thing I have to hand is Samsung Note 2 and THEIR (admittedly bloated) version of Android-4.4.2 is 5.78G. I'd stay with the builtin browser if I could.

Do you think I should update/upgrade ?

Is it possible given the low specification of my tablet ?

Personally, I doubt if you have the option. That came out in 2012, so it's probably 4-5 years old. If you have an sdcard, you can go through the applications, and 'move to sdcard' where the option exists. Get security updates, but don't try, as they say 'making a silk purse out of a sow's ear.' If your own manufacturer does an OS update I'd consider it. I wouldn't try to shoehorn in some generic thing, as you'd be tortured for drivers.